The phrase "biting off too much" refers to taking on more than one can handle or being overambitious. Antonyms of this phrase could be "taking on manageable tasks," "setting realistic goals," or "staying within one's limits." Other antonyms could include "being patient," "taking things one step at a time," or "being content with what one has accomplished." Instead of rushing into things, it's important to be mindful of one's abilities and not take on more than can be feasibly accomplished. By taking a more measured approach, success can be achieved without feeling overwhelmed or burned out.